1. Technical Field
This disclosure relates to imaging and more particularly, to a method and apparatus for registering magnetic resonance and CT scan images.
2. Description of the Related Art
Medical imaging of internal organs may be performed by non-invasive imaging procedures, such as computed topography (CT, or xe2x80x9cCat scanxe2x80x9d) and magnetic resonance (MR) imaging (MRI). These techniques provide useful information about internal organs which may be employed by medical personnel to make important health related decisions about a patients condition.
Although these techniques both provide useful information, each techniques may be limited by the by the type of information the technique can provide. For example, CT imaging provides topographical images of internal structures of tissue. This means the shape or geometry of an internal organ can be determined using the CT procedure. MR imaging on the other hand provides functional information about the tissue comprising the organ or internal structure. For example, MR images may be employed to determine whether tissue is alive or dead for a given internal organ.
Therefore, a need exists for a method and apparatus with the capability of combining MR and CT information for an improved image having both shape and function information about organic structures and tissues.
A method for registration of magnetic resonance (MR) and computed topography (CT) images, in accordance with the present invention includes providing MR images having a region of interest delineated by first contours and providing CT images having the region of interest delineated by second contours. A pre-existing model of the region of interest is also provided. The pre-existing model is fit to the first contours or the second contours to provide a first resultant model. The first resultant model is then copied to provide a copied model. The copied model is fit to the other of the first contours and the second contours to provide a second resultant model. By rotating and translating the first resultant model and/or the second resultant model, the first resultant model and the second resultant model are registered. The rotation and translation information are stored and applied to the images to provide registration between the MR images and the CT images.
In other methods, the step of providing MR images having a region of interest delineated by first contours preferably includes the step of providing MR images from a plurality of positions. The step of providing MR images having a region of interest delineated by first contours may include the step of manually delineating the region of interest or automatically delineating the region of interest by employing an segmentation algorithm. The step of providing CT images having the region of interest delineated by second contours may include the step of manually delineating the region of interest or automatically delineating the region of interest by employing an segmentation algorithm. The MR images and CT images are preferably acquired from a beating heart. The CT images may be acquired at a rate of greater than or equal to eight images per second.
In still other methods, the step of fitting the preexisting model to one of the first contours and the second contours to provide a first resultant model may include the steps of rigidly translating and rotating the pre-existing model, adjusting global shape parameters of the pre-existing model and conforming a mesh of springs of the pre-existing model to accommodate individual features described by one of the first and second contours. The step of fitting the copied model may include the steps of rigidly translating and rotating the copied model, adjusting global shape parameters of the copied model and conforming a mesh of springs of the copied model to accommodate individual features described by the other of the first and second contours. The method may include the step of determining volumes of features in the MR and CT images by summing voxels in the first and second resultant models, respectively.
A method for registration of magnetic resonance (MR) and computed topography (CT) images, in accordance with the present invention includes providing MR and CT images of a heart, delineating an epicardial surface and an endocardial surface of the heart in the MR and CT images by designating contours on the images and providing a pre-existing heart model. The pre-existing heart model is fit to the contours in the MR images to provide an MR model, and the MR model is copied to provide a copied MR model. The copied MR model is fit to contours in the CR images to provide a CT model. One of the MR model and the CT model are rotated and translated to register the MR model and the CT model. The rotation and translation information are stored, and the rotation and translation information are applied to the MR and CT images to provide registration between the MR images and the CT images.
In other methods, the step of delineating an epicardial surface and an endocardial surface of the heart may includes the step of manually delineating the epicardial surface and the endocardial surface or automatically delineating the epicardial surface and the endocardial surface by employing an segmentation algorithm. The CT images may be acquired at a rate of greater than or equal to eight images per second. The step of fitting the pre-existing model to the contours of the MR images may include the steps of rigidly translating and rotating the pre-existing model, adjusting global shape parameters of the pre-existing model and conforming a mesh of springs of the pre-existing model to accommodate individual features described by the contours in the MR images. The step of fitting the copied MR model to the contours of the CT images may include the steps of rigidly translating and rotating the copied MR model, adjusting global shape parameters of the copied MR model and conforming a mesh of springs of the copied MR model to accommodate individual features described by the contours in the CT images. The step of determining volumes of a left ventricle blood pool and myocardium in the MR and CT images by summing voxels in the MR and CT models, respectively, may be included.
The steps of the present invention may be implemented by a program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps for registration of magnetic resonance (MR) and computed topography (CT) images.
A system for registration of magnetic resonance (MR) and computed topography (CT) images, in accordance with the present invention, includes means for delineating an epicardial surface and an endocardial surface of a heart in MR and CT images by designating contours on the images. A pre-existing heart model is employed for fitting to the contours in the MR images to provide an MR model. Means for copying the MR model to provide a copied MR model is included. The copied MR model is fit to contours in the CR images to provide a CT model. Means for rotating and translating the MR model and the CT model to register the MR model and the CT model is included. A memory is employed for storing rotation and translation information such that the rotation and translation information is applied to the MR and CT images to provide registration between the MR images and the CT images, and a display is included for viewing the registered MR images and CT images.
In alternate embodiments, the means for delineating may include a mouse and a graphical user interface. The means for copying may include a processor. The means for rotating and translating may also include a processor. The pre-existing model preferably includes a mesh of springs to accommodate individual features described by the contours in the MR images. The copied MR model may includes a mesh of springs of the copied MR model to accommodate individual features described by the contours in the CT images. The MR and CT models may include voxels for determining volumes in the MR and CT.